Problem

[Maxin]

After I launch the DI.FM app and want to visit other apps same time,the phone just stop the playing the launched channel. Never happened something like this before at any other devices.

[Uliwooly]

@Maxin

That's an issue with the app, things to try

uninstall > re-install the app > if that doesn't solve the problem, contact the app developers as its up to them to address this issue, not Sony. 

[Maxin]

Reinstalled. Same issue. Tried to launch the same app on other device and no problem at all.working perfectly.

[Uliwooly]

@Maxin

Exactly, you have to contact the app developer, as there's a compatibility issue. 

[Uliwooly]

@Maxin

One more thing to try, disable Ok Google

Settings > language & input > voice input > Enhanced google services > settings > OK google detection

[Maxin]

Sorted out! Problem came from another app-clean master.Just deleted the app.

What to do now with the my music that plays 7 seconds?

[Uliwooly]

@Maxin

Check if there's another intrusive app, perhaps a taskiller or antivirus